1. Field of the Invention
The present invention concerns a roller pump that performs pumping action pressing an elastic tube installed in the roller pump with a roller rotation apparatus. Particularly, the present invention concerns an improvement of such a roller pump suitable for medical application.
2. Description of the Prior Art
In a roller pump of the prior art, a brushless DC motor (for example) is used as a driver that drives the roller pump through a reduction gear with a comparatively large reduction ratio.
Such reduction gear generally comprises a gear train assembled in a separated independent case.
A pump housing, the reduction gear and the motor, each manufactured separately, are connected to compose the roller pump.
An inner surface of the pump housing has a cylindrical form. This cylindrical form is rather complicated. It has a progressively longer radius in the vicinity of inlet and outlet portions of an elastic tube installed along the inner surface of the pump housing, in comparison with the radius in the vicinity of a central portion of the elastic tube, in order to suppress pulsatory motion of a liquid being transferred from the inlet portion toward the outlet portion of the elastic tube.
Further, inlet and outlet slots to insert and fix the inlet and the outlet portions of the elastic tube respectively, and to suppress vibration of the elastic tube during operation, are provided with the pump housing. To install the elastic tube into the pump housing, the inlet and the outlet portions of the elastic tube are inserted and fixed in the inlet and the outlet slots of the pump housing respectively.
In order to make it possible to fix the inlet and the outlet portions of the elastic tube with a different size to the inlet and the outlet slots of the pump housing respectively, such as fixing adapters or levers with springs are used. In the case of the latter, the lever is manually operated to fix each of the inlet and the outlet portions of the elastic tube in the inlet and the outlet slots of the pump housing respectively.
In the roller pump of the prior art as described above, there is a problem that the roller pump comprises a large number of parts and is expensive, since the reduction gear and the pump housing are manufactured separately.
Also in the roller pump of the prior art in which a brushless DC motor is used as the driver, there is a problem that gears of the reduction gear cause a large noise, the gears wear in a comparatively short period, and a large force is required to manually rotate the rotor when it is necessary, since the brushless DC motor is operated at a comparatively high rotation speed that is reduced to a suitable rotation speed for the rotary pump by a reduction gear with a comparatively large reduction ratio.
Also in the roller pump of the prior art in which a stepping motor without a rotation sensor is used as the driver, there is a problem that the efficiency is rather low and a large noise is generated, since it is necessary to use a stepping motor with a larger power than the power required for the rotary pump, in order to prevent such stepping motor from stepping out.
Further, in the roller pump of the prior art, there is a problem that the roller pump is difficult to be manufactured, and therefore it is expensive, since the inner surface of the pump housing has a complicated cylindrical form having a progressively longer radius in the vicinity of the inlet and the outlet portions of the elastic tube installed along the inner surface of the pump housing, in comparison with the radius in the vicinity of the central portion of the elastic tube, in order to suppress pulsatory motion of the liquid being transferred from the inlet portion toward the outlet portion of the elastic tube.
Further, in the roller pump of the prior art in which the fixing adapters corresponding to the size of the elastic tube are used for inserting and fixing the inlet and the outlet portions of the elastic tube to the inlet and the outlet slots of the pump housing respectively, there is a problem that the fixing adapter is often removed together with the elastic tube when only the latter is to be removed.
Also in the roller pump of the prior art in which the levers with springs are used for fixing the inlet and the outlet portions of the elastic tube to the inlet and the outlet slots of the pump housing respectively, there is a problem that the installing operation of the elastic tube is troublesome, since it is necessary to grasp the elastic tube with one hand and handle the lever with another hand.